1. Field of the Invention
The invention relates to vessels for anaerobic fermentation, and particularly to closed vessels with improved sealing means.
2. Related Art
It is already known to provide a device for extracting material in the form of a powder or in the form of particles, in a vessel or circular or polygonal cross-section having a bottom consisting of a flat plate. The known extraction device is in the form of a frame sliding on the flat plate and associated with several upwardly open channels, which are parallel to the flat plate of the vessel.
The known extraction device operates in the following manner: the frame sliding on the flat plate sweeps the material until it falls into the upwardly open channels. Then, the transport screws displace the material towards openings provided at the side, under the flat plate of the vessel.